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1.
超声波处理对麦草碱木质素结构特性的影响 总被引：1，自引：0，他引：1
采用超声波作用于麦草碱木质素，探讨了超声波对碱木质素的活化作用，用化学法对超声波作用前后碱木质素官能团进行了定量测定，用凝胶色谱（GPC）测定了木质素相对分子质量的变化，用^1H NMR光谱对化学结构进行了分析。结果表明：超声波可以显著提高碱木质素酚羟基和醇羟基含量，当作用时间20min、作用功率200w、液料质量比100：1时，醇羟基含量从1．99mmol／g上升为4．14mmol／g，酚羟基含量从1．88mmol／g上升为2．54mmol／g，羧基含量从0．59mmol／g下降为0．29mmol／g，羰基含量从2．16mmol／g上升为2．68mmol／g。^1H NMR分析表明，愈创木基和紫丁香基峰面积与总峰面积的比值分别从3．61％和0．77％下降为0，甲氧基峰面积与总峰面积的比值从11．50％下降为8．90％。数均分子质量（Mn）和重均分子质量（Mw）分别从1179和10250上升为5031和11605，分散度（Mw／Mn）从8．69下降为2．31． 相似文献
2.
以旱柳落叶为原料，60％乙醇（质量分数，下同）为提取剂，芦丁为标准对照品，研究探索了柳叶中总黄酮的溶剂提取法和超声波辅助提取法的最佳提取条件，并对两种提取方法的提取效果进行了比较。试验表明，溶剂提取法的最佳提取条件为：0．3g柳叶粉末以60％乙醇为溶剂，料液比1：35（g：mL，下同），65℃提取3次，每次75min，总黄酮得率3．83％；超声波辅助提取的最佳条件为：0．3g柳叶粉末以60％乙醇为溶剂，料液比1：35，超声波功率400w，超声波处理3次，每次30min，总黄酮得率4．26％。超声波辅助提取比单纯的溶剂提取缩短了60％的提取时间，得率却提高了11．23％。 相似文献
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4.
利用莎门氏菌B31转化八角茴香中的莽草酸，探讨莽草酸的微生物转化因子。HPLC检测分析结果表明：莎门氏菌B31自身不产莽草酸；菌种在对莽草酸溶液的生物转化过程中，在20-24h莽草酸质量浓度达到最大，莽草酸质量浓度由原溶液中8．04g／L增加到8．80g／L，继续培养，莽草酸出现分解现象；莎门氏菌B31对质量分数为2％的八角糖无转化现象，对八角渣水提液的转化效果最好。以八角渣和蒸馏水的固液比为1：40（g：mL）时的提取液加入莎门氏菌B31培养转化24h后，莽草酸最高质量浓度为0．213g／L，为未转化前莽草酸含量的2．56倍。 相似文献
5.
直接使用超声波处理木质素磺酸钠(LS)水溶液,探索了超声波作用时间、功率以及体系的pH值对超声波作用效果的影响,并通过UV、FT-IR、1H NMR和TGA来考察超声波对木质素磺酸钠物化性能的影响。结果显示:超声波作用15、45、60和120 min,木质素磺酸钠的酚羟基质量分数由0.65%分别提高到0.71%、0.74%、0.81%和0.87%。10 g的LS在100 mL水中经超声波处理,超声波功率从100 W增强到300 W时,酚羟基的质量分数从0.69%提高到0.92%。超声波体系的pH值对超声波结果具有最明显的影响,当用H2SO4调节体系的pH值为0时,超声波处理得到最高质量分数的酚羟基,高达1.58%。UV、FT-IR和1H NMR综合结果显示,超声波对木质素磺酸钠分子的整体结构影响不大,但也会造成局部结构如苯环的部分破裂和磺酸基团的破坏。TGA结果显示超声波对木质素磺酸钠热稳定性能的影响比较复杂,原因是超声波使降解和交联作用同时发生。300 W,20 kHz超声波处理LS水溶液60 min时,超声波的降解效应使超声波木质素磺酸钠(ULS)在200~600℃温度区间的热稳定性低于LS;当超声波150 W40 kHz,pH值为0(浓硫酸调节),超声波处理60 min时处理所得的ULS,交联效应使其在680℃以上高温区的耐热性能比LS有所提高。 相似文献
6.
超声波用于强化有机溶剂提取印楝素 总被引：20，自引：6，他引：20
研究了用超声波强化有机溶剂提取印楝素的工艺过程，分别考察溶剂、料液比、超声波作用时间、超声波功率对提取率的影响实验发现，较理想的提取条件为：13．3g印楝种仁粉，料液比1：2，超声波功率200W；超声波作用时间与溶剂有关。甲醇15min、乙醇20min、乙酸乙酯10min；3种溶剂较佳提取率分别为0．3786％、0．3658％、0．2462％提取样晶利用高效液相色谱仪采用外标法测定提取物中印楝素的含量。实验结果表明，超声波强化提取与搅拌提取相比，不仅缩短了提取时间，而且提取率有所提高。 相似文献
7.
研究了马尾松硫酸浆两段氧脱木质素的最佳工艺条件。结果表明，第一段氧脱木质素的条件为：氧压0．6MPa，温度100℃，时间80min,NaOH 量5％，MgSO4用量0．5％，浆浓10％；第二段氧脱木质素的条件为：氧压0．4MPa，温度90℃，时间60min，NaOH用量3％，MgSO4用量0．5％，浆浓10％。在此条件下，OIOⅡ木质素脱除率达到72．5％，粘度775．2cm^3/g,得率90．5％。经过氧脱木质素后浆的裂断长5．8km，耐破指数5．3kPa.m^2/g，撕裂指数12．7mN.m^2/g。 相似文献
8.
超声波辅助提取松仁蛋白的工艺研究 总被引：1，自引：0，他引：1
对超声波法辅助提取松仁蛋白的工艺进行了研究，得到了超声波辅提松仁蛋白的最佳工艺条件：液料比10：1，提取时间15min，提取功率900W，在此工艺条件下松仁蛋白提取率为97．645％。此法与常规的碱提酸沉法比较，缩短了很长的提取时间，而且大大提高了蛋白质的提取率。 相似文献
9.
沙芥全草总黄酮提取方法及含量测定的研究 总被引：13，自引：0，他引：13
本文采用碱提酸沉法、超声波提取法、甲醇直接提取法、乙醇提取法和热水浸提法对沙芥全草总黄酮进行了提取方法的选择,同时采用硝酸铝比色法进行了总黄酮含量的测定,结果表明:(1)各种方法的提取效率依次为:碱提酸沉法>超声波提取法>甲醇直接提取法>乙醇提取法>热水浸提法;(2)碱提酸沉法提取沙芥总黄酮的提取效率较高,其精密度好,回收率高,适合对沙芥总黄酮的提取,同时采用硝酸铝比色法对总黄酮含量进行测定,其精密度也较高,并测得沙芥全草总黄酮含量为4.8049mg/g,证明其是一种值得开发的药用植物资源。 相似文献
10.
从稻壳中提取木聚糖的研究 总被引：1，自引：0，他引：1
以稻壳为原料，采用制备综纤维素再碱提取的方法，分析了不同碱溶液浓度、温度、固液比和时间对稻壳半纤维素中多戊糖得率的影响。实验结果表明，稻壳中多戊糖含量为19.9％，是较好的木聚糖资源。碱提取稻壳中木聚糖的方法为：预处理：80℃水浸泡3h：碱提取条件：碱质量分数10％，固液比（g：mL）1：10，提取时间3h，提取温度80℃。木聚糖提取率达原料中木聚糖总量的67．50％以上。 相似文献
11.
《Scandinavian Journal of Forest Research》2012,27(5):427-435
In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads. 相似文献
12.
《Scandinavian Journal of Forest Research》2012,27(3):206-217
The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage. 相似文献
13.
《Scandinavian Journal of Forest Research》2012,27(1):53-61
This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland. 相似文献
14.
《Scandinavian Journal of Forest Research》2012,27(1):15-27
The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions. 相似文献
15.
本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。 相似文献
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《Scandinavian Journal of Forest Research》2012,27(5):472-479
Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken. 相似文献
18.
Srisuda Thippayarugs Banyong Toomsan Patma Vityakon Viriya Limpinuntana Aran Patanothai Georg Cadisch 《Agroforestry Systems》2008,72(2):137-148
In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic
or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts
(stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea
(Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content
as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest
N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized
to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea,
largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for
N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant
components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N
released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures
were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality
components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in
the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols.
Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest
age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its
components are mixed. 相似文献
19.
A. Rigueiro-Rodríguez M. R. Mosquera-Losada E. Gatica-Trabanini 《Agroforestry Systems》2000,48(3):245-256
The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste
disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization,
(2) milk sewage sludge at 40 kg N ha−1 target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two
pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha−1. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha−1) + Trifolium repens L. group Ladino (4 kg ha−1) + Trifolium pratense L. var. Marino (1 kg ha−1); (2) Lolium perenne L. var. Tove (25 kg ha−1) + Trifolium repens L. group Ladino (4 kg ha−1) + Trifolium pratense L. var. Marino (1 kg ha−1). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea
(Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m2, with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect
on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage
sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but
affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral
systems.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
20.
《Scandinavian Journal of Forest Research》2012,27(2):166-178
This study investigated the forest history, structural characteristics, the presence of fungal species suggested to indicate ecological continuity in old-growth forest, and the species composition of saproxylic beetles in 30 old forest ''woodland key habitats'' (WKHs), and compared them with production forest in the same age-class in south-eastern Norway. No statistically significant differences in forest characteristics, community of saproxylic beetles or number of red-listed beetles were found between the WKHs and the production forest, probably owing to a combination of profound long-term logging and a lack of will to delineate sufficiently large WKHs in the one area with significantly less forestry impact. The study indicates the advantage of including forest history information in WKH selection where such data exist, and the importance of restoring habitats in heavily exploited forest landscapes. 相似文献